togeomview(1)

NAME

togeomview - send commands or OOGL objects to geomview

SYNOPSIS

togeomview [-c] [-g]  [pipename  [program args ...]]

DESCRIPTION

togeomview sends a stream of geomview commands, or OOGL

format geometric data, to a cooperating copy of geomview. If ge

omview is not running, it is automatically started. ('geomview'

must be on the $PATH of the user running 'togeomview' in order

for this to work.)

Typical usage is:

someprogram | togeomview (to send commands) or someprogram-generating-OOGL-data | togeomview -g (to

send geometry)

i.e. a program pipes geometric data into ``togeomview'';

the data is displayed by a copy of geomview run with the -M op

tion and a name matching the one given to togeomview.

Togeomview uses a named pipe in the directory

/tmp/geomview to communicate with geomview. If unspecified, the

pipe's default name is "OOGL". When sending geometry (-g), a ge

omview object with the same name as the pipe appears in ge

omview's object browser.

By default, when no suitable copy of geomview is running,

togeomview invokes "geomview" with arguments specifying the ap

propriate named pipe. A different command may be specified as

in:

togeomview OOGL gv -wpos 300x300 -c

my_startup_script

which communicates through a pipe named OOGL, and (if nec

essary) invokes the given gv command. The pipe name is required

if a command is specified.

After togeomview has created it, the named pipe may be

written as an ordinary file. For example, one could use

togeomview pipename < /dev/null

to invoke a listening copy of geomview, and then run a

program which simply wrote to /tmp/geomview/pipename.

FILES

/tmp/geomview

BUGS

The pipe-based communications scheme imposes several re

strictions.

If no copy of geomview is reading from the pipe, or if ge

omview gets far enough behind, a program writing data to

``togeomview'' will be forced to block after sending a few kilo

bytes.

Because of the buffering in the pipe, the sender may be

substantially ahead of the geomview display.

If geomview exits, the sending program receives a write

on-broken-pipe (SIGPIPE) signal, which will kill it unless mea

sures are taken to catch or ignore that signal.

Only one copy of geomview can read from a given pipe at a

time. If a second copy attempts to read from it, both will prob

ably fail. It's fine to have multiple copies of geomview reading

from different pipes.

Note that togeomview will invoke geomview if no extant

copy is listening to the relevant pipe; it can't connect to an

existing copy of geomview started by other means.

SEE ALSO

geomview(1), oogl(5)

Geometry Center 21 May 1993

TOGEOMVIEW(1)